In electric and electronic circuits a plurality of different components is used for providing a particular function. In dependence on the type of the respective component and the load of the components in connection with the electric values of current and voltage, at least some of the components constitute heat sources of different thermal capacity and thus different heat transfer. Especially semiconductor components and specifically power transistors show particular electric dissipation losses which are dependent on the type and the operation and are not to be neglected so that partly considerable heating occurs. The heat must be dissipated during operation of the respective components so as to prevent inadmissible heating and, consequently, damage or destruction of the components.
In circuits for the control of electric motors for example signals clocked for power matching or power control of the respective electric motors are used, thereby the active components such as the transistors (power semiconductors) and electrolyte capacitors exhibiting increased power dissipation so that cooling is indispensable. For this purpose the components exhibiting respective power dissipation and thus emitting heat are cooled and are frequently mechanically and, resp., thermally connected to a so called heat sink.
A heat sink constitutes a means consisting of a proper heat-conducting material and increasing the surface required for the emission of heat so that the heat of the component to be cooled is absorbed and is efficiently emitted to the air, for example, by means of natural convection or with the aid of a ventilator. Also other coolants can be used, for instance in the form of liquid. It is essential that the active surface for the emission of heat of the component is increased and the heat is withdrawn from the component by the properly heat-conducting material of the heat sink. Heat sinks are generally made of metal such as copper or aluminum, wherein also the design of the surface influences the heat emission.
A basic and known arrangement of a component A to be cooled in connection with an arrangement on a heat sink B is shown in a simplified and schematic manner in FIG. 8. The component to be cooled can be a power transistor, for example.
In this case, on a printed circuit board C the heat sink B is arranged. The heat sink B is provided in thermal contact with the component A arranged on the heat sink B.
Preferably the component A can be arranged to be insulated against the heat sink B by means of an insulating layer D, wherein the insulating layer D is to be electrically non-conducting but adequately heat-conducting.
The component A can be electrically connected to the printed circuit board C by means of appropriate connecting elements E for providing the respective function.
FIG. 8A illustrates a sectional view along the sectional line Y-Y according to FIG. 8B (the component A is not shown in a cut view in this context) and FIG. 8B illustrates a sectional view along the line X-X according to FIG. 8A. The heat sink B includes full-surface branches G which are structured so that they increase the active surface for heat emission of the heat absorbed by the component A.
If power dissipation and thus heat occurs in the component A during operation, this heat is emitted to the heat sink B via the insulating layer D, and the heat sink B in turn emits the heat extensively to the environment via the branches G. In this manner the heating of the component A can be kept within reasonable limits so that the component A is prevented from being destroyed or damaged.
If more heat is to be removed due to higher power dissipation, a larger heat sink or, dependent on the heat to be removed, also active ventilation by means of a ventilator or another preferably fluid coolant is required.
In this context, the document EP 1 750 302 A1 discloses an electric component arrangement in which a plurality of substantially electronic components, which can be respective power components and constitute a heat source, on the one hand are retained in position by means of a spring comb made of metal and, on the other hand, can be cooled via the spring comb contacting the component. This cooling takes place in addition to the cooling of the respective components by means of a heat sink onto which the components are pressed by means of the spring comb. The entire arrangement is mounted in a closed casing in this form.
The document DE 102 25 993 A1 discloses a heat sink having a body and wherein a heat-emitting component is pressed onto the body by means of a mechanical means for providing a thermal contact. The mechanical means comprises a spring element which is attached to a pin by an aperture arranged therein and is held by means of the pin and at the same time contacts the component to be cooled and presses the same to the body. For applying the pressing force the mechanical element is attached to the pin in such way that, in connection with the aperture into which the pin protrudes, tilting occurs and thus a moment (force) can be exerted on the component. The heat of the component is emitted to the body by the thermal contact with the latter.
Finally the document EP 1 091 403 A2 discloses the arrangement of a heat sink, wherein the heat sink is structured in such manner that on a base plate a plurality of lamellas are arranged and the lamellas are aligned with each other in plural rows and in their longitudinal orientation so that an airflow required for cooling can pass through the plural rows of lamellas. The lamellas can be made of planar or curved elements and can have further bent areas for influencing a cooling airflow at the end distant from the base plate.
The afore-considered known devices of heat sinks or cooling arrangements for electric or electronic components are structured so that a compact design is hardly possible by the arrangement of at least one or more cooling devices in a small space within a casing. The afore-described arrangements require a particular size and, resp., a particular space in accordance with the respective configurations of the heat sinks so as to achieve sufficient cooling effect by natural or forced convection.